Finecast Foundry Ltd have developed a gearbox consisting of 5 main castings and fragile internal cores (printed using cerabead to offer a more robust solution).
Component
Gearbox assembly for the automotive sector, in A356 aluminium alloy, consisting of five main castings, each with very high dimensional tolerances.
Challenges
- Complex internal core geometry, with risks of gas being trapped during casting and core cracking.
- High internal core dimensional accuracy required.
- High casting integrity requirements.
- X-ray inspection: AMS STD 2175 Class 1 Grade C.
- Casting to resist leak testing confirmed by pressure testing to 20 Bar.
Method
- Close collaboration with customer to optimise design for casting with additional bosses to provide core support.
- Casting simulation used to confirm filling geometry, reduce liquid metal turbulence and optimise methoding design to reduce risk of shrinkage porosity.
- Chemically bonded sand casting used to produce casting mould.
- Cerabead cores used to reduce risk of core cracking during casting and optimise dimensional control.
- Cores design with small vents to reduce risk of gas entrainment.
- 3D printed cores to increase strength and steel guide pins employed to minimise assembly variability.
- GOM scanning of mould and core assembly prior to casting to ensure mould accuracy.
- HIPping of casting completed prior to pressure testing to 20 bar.
- Visual and full NDT inspection to ensure customer specification achieved.
